An international conference focused on properties and functional role of protein phosphatases in heart and vascular smooth muscle will be held for 5 days (Aug. 19-23, 1985) at the Belgian Royal Academy of Medicine (Brussels) and the Katholieke Universiteit Leuven, Belgium. The conference is a satellite of the International Union of Biological Chemists meeting in Amsterdam (Aug. 25-30, 1985), and provides an unusual opportunity for leading biochemists and physiologists to engage in active and meaningful discussion of facts, hypotheses and future directions of research. It will also encourage young and promising scientists to attend and share views on functional aspects of protein phosphorylation-dephosphorylation. The conference includes 4 morning and 4 afternoon sessions devoted to 32-36 speaker presentations and 2 poster sessions for related studies (30 posters) not explicitly covered by speakers. The conference is timely because many advances have been realized in the last several years regarding structure and regulation of protein phosphatases. Moreover, it is increasingly clear that regulation of arterial contractility involves phosphorylation and DEPHOSPHORYLATION of contractile proteins, membrane proteins, and key metabolic enzymes. The objectives are to: (1) establish a background for interpreting physiological significances of protein phosphatases by summarizing properties and functional roles of specific site phosphorylation of purified proteins in vitro and of relevant proteins in vivo, (2) provide an updated review of recent advances with respect to subunit structure, substrate specificity and biochemical regulation of phosphatases, and (3) integrate data from in vitro and in vivo studies in order to elucidate further the role of phosphorylation/dephosphorylation in myocardial and arterial contractility. A broad base of information is envisioned to permit comparisons between different systems, and thereby identify common principles and mechanisms. We anticipate that limiting attendance to 70-80 participants will maximize exchange of data and ideas. Abstracts of all presentations will be distributed to participants at the beginning of the conference. The proceedings will be published shortly after the conference permitting transmittal of the collected updated information to a wide audience.